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Test Code WEEPC Western Equine Encephalitis Antibody Panel, IgG and IgM, Spinal Fluid

Useful For

Aiding the diagnosis of Western equine encephalitis

Method Name

Immunofluorescence Assay (IFA)

Reporting Name

West Equine Enceph Ab Panel, CSF

Specimen Type

CSF


Advisory Information


This test is not available for specimens originating in New York.



Specimen Required


Container/Tube: Sterile vial

Specimen Volume: 0.5 mL

Additional Information: This test is not available for specimens originating in New York.


Specimen Minimum Volume

0.2 mL

Specimen Stability Information

Specimen Type Temperature Time
CSF Refrigerated (preferred) 14 days
  Frozen  14 days

Reject Due To

Hemolysis

Mild OK; Gross OK

Lipemia

Mild OK; Gross OK

Icterus

NA

Other

NA

Clinical Information

The virus that causes Western equine encephalitis (WEE) is widely distributed throughout the United States and Canada; disease occurs almost exclusively in the western states and Canadian provinces. The relative absence of the disease in the eastern United States probably reflects a paucity of the vector mosquito species, Culex tarsalis, and possibly a lower pathogenicity of local virus strains.

 

The disease usually begins suddenly with malaise, fever, and headache, often with nausea and vomiting. Vertigo, photophobia, sore throat, respiratory symptoms, abdominal pain, and myalgia are also common. Over a few days, the headache intensifies; drowsiness and restlessness may merge into a coma in severe cases. In infants and children, the onset may be more abrupt than for adults. WEE should be suspected in any case of febrile central nervous system (CNS) disease from an endemic area. Infants are highly susceptible to CNS disease and about 20% of cases are under 1 year of age. There is an excess of males with WEE clinical encephalitis, averaging about twice the number of infections detected in females. After recovery from the acute disease, patients may require from several months to 2 years to overcome the fatigue, headache, and irritability. Infants and children are at a higher risk of permanent brain damage after recovery than adults.

 

Infections with arboviruses can occur at any age. The age distribution depends on the degree of exposure to the particular transmitting arthropod relating to age, sex, and occupational, vocational, and recreational habits of the individuals. Once humans have been infected, the severity of the host response may be influenced by age. WEE tends to produce the most severe clinical infections in young persons.

Reference Values

IgG: <1:10

IgM: <1:10

Reference values apply to all ages.

Interpretation

Detection of organism-specific antibodies in the cerebrospinal fluid (CSF) may suggest central nervous system (CNS) infection. However, these results are unable to distinguish between intrathecal antibodies and serum antibodies introduced into the CSF at the time of lumbar puncture or from a breakdown in the blood-brain barrier. The results should be interpreted with other laboratory and clinical data prior to a diagnosis of CNS infection.

Cautions

All results must be correlated with clinical history and other data available to the attending physician.

 

False-positive results may be caused by breakdown of the blood-brain barrier, or by the introduction of blood into the cerebrospinal fluid at collection.

 

Western equine encephalitis and Eastern equine encephalitis viruses show some cross-reactivity; however, antibody response to the infecting virus is typically at least 8-fold higher.

Clinical Reference

1. Gonzalez-Scarano F, Nathanson N: Bunyaviruses. In Fields Virology. Vol 1. Second edition. Edited by BN Fields, DM Knipe. New York, Raven Press, 1990, pp 1195-1228

2. Donat JF, Rhodes KH, Groover RV, Smith TF: Etiology and outcome in 42 children with acute nonbacterial meningoencephalitits. Mayo Clin Proc 1980;55:156-160

3. Tsai TF: Arboviruses. In Manual of Clinical Microbiology. Seventh edition. Edited by PR Murray, EJ Baron, MA Pfaller, et al. Washington, DC, ASM Press, 1999, pp 1107-1124

4. Calisher CH: Medically important arboviruses of the United States and Canada. Clin Microbiol Rev 1994;7:89-116

Method Description

Dilutions of cerebrospinal fluid (CSF) are prepared and allowed to react with substrate cells infected with the appropriate arbovirus. If antibodies to this virus are present in the CSF of the patient, an antigen-antibody complex will develop that can be detected by a fluorescein-labeled antibody directed to human globulin.(Tsai TF: Arboviruses. In Manual of Clinical Microbiology. Seventh edition. Edited by PR Murray, EJ Baron, MA Pfaller, et al. Washington, DC, ASM Press, 1999, pp 1107-1124; Beaty BJ, Casals J, Brown KL, et al: Indirect fluorescent-antibody technique for serological diagnosis of LaCrosse [California] virus infections. J Clin Microbiol 1982;15:429-434)

Day(s) and Time(s) Performed

May through October: Monday through Friday; 9 a.m.

November through April: Monday, Wednesday, Friday; 9 a.m.

Analytic Time

Same day/1 day

Specimen Retention Time

2 weeks

Performing Laboratory

Mayo Medical Laboratories in Rochester

Test Classification

This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the U.S. Food and Drug Administration.

CPT Code Information

86654 x 2

LOINC Code Information

Test ID Test Order Name Order LOINC Value
WEEPC West Equine Enceph Ab Panel, CSF 69036-2

 

Result ID Test Result Name Result LOINC Value
26371 West Equine Enceph Ab, IgG, CSF 9315-3
26372 West Equine Enceph Ab, IgM, CSF 9316-1